Conventional polishing pads for chemical-mechanical planarization (CMP) may include a composite of a first porous or filler-dispersed polymeric layer stacked with a second, soft layer. As reported in U.S. Pat. No. 5,257,478, the soft second layer has what was termed as a different hydrostatic modulus from the first layer and serving as a pressure equalizer to provide equal pressures across the semiconductor surface for uniform polish. When the second soft layer in a CMP pad is absent the uniformity of the polished wafer may deteriorate.
A third layer of adhesive may be applied to the second layer for the purpose of attaching the composite pad to the polishing tool. However, the use of a three layer structure in the conventional pad may increase the risk of separation or delamination between layers during polish. In addition, the three layer structure may entrap air bubbles or extraneous contaminants between layers resulting in difficult to detect protrusions on the pad surface, which may lead to scratching defects and non-uniformity of polish.